What explains the underlying causes of rural–urban differentials in severe acute malnutrition (SAM) among under-five children is poorly exploited, operationalized, studied and understood in low- and middle-income countries (LMIC). We decomposed the rural–urban inequalities in the associated factors of SAM while controlling for individual, household, and neighbourhood factors using datasets from successive demographic and health survey conducted between 2010 and 2018 in 51 LMIC. The data consisted of 532,680 under-five children nested within 55,823 neighbourhoods across the 51 countries. We applied the Blinder–Oaxaca decomposition technique to quantify the contribution of various associated factors to the observed rural–urban disparities in SAM. In all, 69% of the children lived in rural areas, ranging from 16% in Gabon to 81% in Chad. The overall prevalence of SAM among rural children was 4.8% compared with 4.2% among urban children. SAM prevalence in rural areas was highest in Timor-Leste (11.1%) while the highest urban prevalence was in Honduras (8.5%). Nine countries had statistically significant pro-rural (significantly higher odds of SAM in rural areas) inequality while only Tajikistan and Malawi showed statistically significant pro-urban inequality (p < 0.05). Overall, neighbourhood socioeconomic status, wealth index, toilet types and sources of drinking water were the most significant contributors to pro-rural inequalities. Other contributors to the pro-rural inequalities are birth weight, maternal age and maternal education. Pro-urban inequalities were mostly affected by neighbourhood socioeconomic status and wealth index. Having SAM among under-five children was explained by the individual-, household- and neighbourhood-level factors. However, we found variations in the contributions of these factors. The rural–urban dichotomy in the prevalence of SAM was generally significant with higher odds found in the rural areas. Our findings suggest the need for urgent intervention on child nutrition in the rural areas of most LMIC.

在低收入和中等收入国家 (LMIC)，五岁以下儿童严重急性营养不良 (SAM) 城乡差异的根本原因尚未被充分利用、实施、研究和理解。我们使用 2010 年至 2018 年在 51 个中低收入国家进行的连续人口和健康调查的数据集，分解了 SAM 相关因素中的城乡不平等，同时控制了个人、家庭和社区因素。该数据包含 51 个国家 55,823 个社区内的 532,680 名五岁以下儿童。我们应用 Blinder-Oaxaca 分解技术来量化各种相关因素对 SAM 中观察到的城乡差异的贡献。总的来说，69% 的儿童生活在农村地区，从加蓬的 16% 到乍得的 81%。农村儿童 SAM 总体患病率为 4.8%，而城市儿童为 4.2%。东帝汶农村地区的 SAM 患病率最高（11.1%），而洪都拉斯的城市患病率最高（8.5%）。九个国家存在统计显着的有利于农村的不平等（农村地区 SAM 的几率显着较高），而只有塔吉克斯坦和马拉维表现出统计显着的有利于城市的不平等（p < 0.05  ）。总体而言，社区社会经济地位、财富指数、厕所类型和饮用水来源是造成农村不平等的最重要因素。造成农村不平等的其他因素包括出生体重、母亲年龄和母亲教育程度。亲城市的不平等主要受到社区社会经济地位和财富指数的影响。五岁以下儿童出现 SAM 的原因有个人、家庭和社区层面的因素。然而，我们发现这些因素的贡献存在差异。SAM 患病率的城乡二分法通常很显着，农村地区的患病率较高。我们的研究结果表明，大多数中低收入国家的农村地区需要对儿童营养进行紧急干预。